A barrier layer is formed within a microfabricated device, such as a semiconductor laser assembly. The barrier layer is used to separate bonding material from an underlying layer that is located beneath the barrier layer. The barrier layer includes at least three thin layers that have alternating levels of electronegativity. Therefore, a significant amount of intermetallics are formed between the thin layers, thereby creating strong bonds between the thin layers at relatively low temperatures. It is difficult for the bonding material to break the strong bonds of the thin layers, and the bonding material is, therefore, prevented from penetrating the barrier layer and reacting with the underlying layer.